Device for cleaning the wall of a silo

ABSTRACT

Device for cleaning the wall (1, 23) of a silo, comprising a compressed-air gun (12) suspended from two cables (14, 15) which are connected to two separate winches (16, 17), bearing on two pulleys (9, 10) fastened to a frame (6) which is arranged inside the silo and which is fixed to a rotary plate (4) which can move on a circular track (5) above an opening (2) in the silo.

FIELD OF THE INVENTION

The invention relates to the cleaning of silos used for storingindustrial products such as, for example, sodium carbonate.

It relates more particular to a device for cleaning such a silo.

TECHNOLOGY REVIEW

Silos intended for storing industrial products must be cleanedperiodically. Thus some industrial products, especially powdered sodiumcarbonate, have the tendency, under the effect of gravitational forces,to stick together and to form encrustations on the wall of the silo.Depending on the case, these encrustations generally tend to increase insize over the course of time, so that they reduce, sometimesconsiderably, the working capacity of the silos and run the risk, in thelong-term, of blocking up the draw-off chutes.

A first method used for detaching encrustations from the wall of a siloconsists in striking them by means of a manually operated percussiontool. This method implies the presence of an operator inside the silo,something which is dangerous and is generally proscribed by safetyregulations in the case of large silos.

It has also been proposed to detach the encrustations, by means of amilling cutter which is moved along the wall. A known device, designedfor this purpose, comprises a metal frame which can move inside thesilo, carrying the milling cutter, the frame being able to rotatethrough 360 degrees on a circular running track arranged above anopening in the silo [NORTHERN VIBRATOR MANUFACTURING LTD Brochure,Gyro-Whip Bin Cleaning Systems, Northern Vibrator Mfg. Ltd., Georgetown,Ontario, Canada; Patent GB-2,146,264 (NORTHERN VIBRATOR Mfg. Ltd.)].This known device has the advantage of being able to be operated fromoutside the silo. However, it is difficult to handle, its productivityis low and the milling cutter risks, moreover, damaging the wall of thesilo.

In order to avoid the problems associated with the use of a millingcutter, it has been envisaged to detach the encrustations by means of acompressed-air gun mounted at the end of a jib which can be operatedmanually inside the silo from a manhole made in the wall of the silo(AIRNESCO Brochure, Technical Information and Operating Instructions,The Airnesco Bunker lances N2, N3 and N4, Airnesco InternationalLimited, Rochester, Kent, England). This known means has the drawback ofbeing difficult, imprecise and tiring to handle.

SUMMARY OF THE INVENTION

The invention remedies the aforementioned drawbacks by providing a noveldevice for cleaning silos, the handling of which is easy and precise,which is effective and has an optimum productivity and with which therisk of damaging the wall of the silo is a minimum.

The invention therefore relates to a device for cleaning the wall of asilo, comprising a compressed-air gun which can move inside the silo,the gun being suspended for this purpose from two cables which are fixedrespectively on either side of its centre of gravity and which areconnected respectively to two winches, bearing respectively on twopulleys fastened to a frame which is arranged inside the silo and whichis fixed to a rotary plate which can move on a circular track above anopening in the silo.

BRIEF DESCRIPTION OF THE DRAWING

The FIGURE shows partially, in vertical axial section, the upper regionof a silo whose side wall (1) is pierced in its upper part by a manhole(2). An agglomeration (3) of a solid substance adheres to the wall (1).In order to detach the agglomeration (3) from the wall, a device inaccordance with the invention is inserted into the silo via the manhole(2). The illustrated device is described below.

DETAILED DESCRIPTION OF THE INVENTION

In the device according to the invention, the compressed-air gun is anapparatus well known from a technical standpoint, which is designed toblast, in a defined direction, a blast of compressed air. The flow rateof the blast of compressed air, its temperature and its pressure may allbe regulated as required, using a compressor, valves and a pressureregulator, depending on the magnitude of the encrustations to bedetached and on the nature of these encrustations. In practice, it ispossible, for example, to regulate the pressure of the compressed airbetween 0.4 and 1.5 MPa. Examples of compressed-air guns which can beused in the device according to the invention are described in theaforementioned AIRNESCO brochure and in Document GB-A-686842 (AIRNESCO).

The compressed-air gun is suspended in the silo by two cables connectedrespectively to two separate winches. The two cables are fixed to thegun, respectively on either side of the centre of gravity of the gun.The winches move the gun vertically inside the silo. Since the winchescan be operated separately, they allow moreover the gun to be pivotedthrough 180 degrees in the vertical plane.

The frame and the rotary plate have the function of orienting the gun inthe horizontal plane. For this purpose, the cables supporting the gunbear separately on two separate pulleys on the frame so that themovement of the plate on the circular and generally horizontal trackrotates the frame and the gun through 360 degrees about a vertical axis.

By combining the operation of the winches with the operation of therotary plate, it is possible to position the gun in an optimum fashionwith respect to an encrustation to be detached from the wall.Furthermore, by an appropriate operation of the winches, it is possibleto orient, as required, the angle of the blast of compressed air blastedonto the encrustation to be treated.

In the device according to the invention, the winches and at least oneof the pulleys are preferably arranged in the immediate vicinity of thevertical passing through the centre of the aforementioned circulartrack.

In one particular embodiment of the device according to the invention,one of the pulleys is mounted at one end of a jib which is pivoted tothe frame at its other end. In this embodiment of the invention, thepivoting of the jib to the frame is designed so as to allow rotation ofthe jib about a horizontal axis in order to move the gun further awayfrom or closer to the wall of the silo.

In the device according to the invention and its particular embodimentwhich has just been described, the winches may advantageously bearranged outside the silo and the cables then pass through a centralopening in the rotary plate which, for this purpose, is annular.

In another embodiment of the device according to the invention, thecompressed-air gun includes a stabilizing weight. The function of thisis to absorb, by inertia, the reaction force of the blast of compressedair on the gun so as to reduce the amplitude of oscillations of the gunand to stabilize it in the silo.

In a further embodiment of the device according to the invention, thecompressed-air gun carries a television camera connected to a receiverlocated outside the silo. In this embodiment of the device according tothe invention, the television camera is oriented towards the front ofthe gun and its function is to display the front of the encrustationsubjected to the blast of compressed air. The television cameratherefore allows permanent visual monitoring of the wall of the silo,thereby making it much easier to operate the winches and the frame inorder to alter the position and orientation of the gun.

The device according to the invention is applicable to the cleaning ofany silo containing an industrial product, for example grain, coal orore silos. It finds one particular application in disencrusting siloswhich are used for storing powdered sodium carbonate.

DESCRIPTION OF A PREFERRED EMBODIMENT

Particular features and details of the invention will emerge from thefollowing description of the single FIGURE of the appended drawing,which shows a preferred embodiment of the device according to theinvention during use in a silo.

The FIGURE shows partially, in vertical axial section, the upper regionof a silo whose side wall 1 is pierced in its upper part by a manhole 2.An agglomeration 3 of a solid substance (for example sodium carbonate)is adhering to the wall 1. In order to detach the agglomeration 3 fromthe wall, a device in accordance with the invention is inserted into thesilo via the manhole 2. This device comprises a rotary annular plate 4based on a horizontal circular track 5 made on the periphery of themanhole 2. The circular track 5 and the plate 4 are designed to allowthe plate to rotate through 60 degrees on the circular track 5. Theplate 4 carries a frame 6 of metal beams inside the silo. A jib 7 ispivoted to the frame 6 on a ball joint 8 so that it can pivot in avertical plane about a horizontal axis. A pulley 9 is fixed to the freeend of the jib 7 and three coaxial and independent pulleys 10 are fixedto the frame 6 beneath the central opening 24 in the annular plate 4.The pulleys 10 are positioned substantially on the vertical axis passingthrough the centre of the circular track 5. The inclination of the jib 7is controlled by means of a cable 18 which is connected, via one of thethree pulleys 10, to a winch 19 located outside the silo, above themanhole 2.

An arm 11, carrying a compressed-air gun 12 and a balance weight 13, issuspended in the silo from two cables 14 and 15 which pass through thecentral opening 24 in the annular plate 4 and are connected respectivelyto two separate winches 16 and 17 located outside the silo, above themanhole 2, in the immediate vicinity of the vertical axis of thecircular track 5. The cables 14 and 15 are fixed respectively on eitherside of the centre of gravity of the assembly formed by the arm 11, thegun 12 and the balance weight 13. They bear respectively on two of thethree pulleys 10, the cable 14 moreover bearing on the pulley 9. The gun12 carries a television camera 20 oriented towards the front of the gun.A hose 21 passing through the opening 24 in the plate 4 is fixed to thearm 11. This hose contains a conduit for supplying the gun 12 withcompressed air produced by a compressor, not shown, located outside thesilo. The hose 21 furthermore contains a cable for connecting the camera20 to a television receiver, not shown, located outside the silo.

In order to detach the agglomeration 3 from the wall 1 of the silo, thegun 12 is firstly brought opposite a region 22 of the agglomeration tobe attacked. For this purpose, the plate 4 is suitably oriented on thetrack 5 in order to bring the gun into the vertical axial plane of theregion 22 and the winches 16, 17 and 19 are operated in order to bringthe gun 12 level with the region 22. Moreover, by combining theactuation of the winches 16, 17 and 19, the height of the gun in thesilo, its distance from the wall and its inclination are altered asrequired, it is especially possible, by means of the winches 16 and 17,to orient the arm 11 so that it occupies a horizontal position (as shownin the FIGURE), a position in which the gun 12 is directed obliquelydownwards, or a position in which the gun is directed obliquely upwards.It is advantageous to be able to orient the gun 12 obliquely in order toattack an oblique face of the agglomeration 3 or to clean an inclinedface 23 of the wall. The camera 20 allows the optimum position of thegun 12 to be found easily and precisely.

When the gun 12 has reached the correct position facing theagglomeration 3, it is brought into communication with the compressor soas to blast the region 22 of the agglomeration 3 with a blast ofcompressed air. The camera 20 allows the action of the blast ofcompressed air on the agglomeration to be monitored. As the pieces ofagglomeration 3 are detached under the effect of the blast of compressedair (which is sent by successive pulses), the position and orientationof the gun 12 are altered by means of the plate 4 and the winches 16, 17and 19.

In order to insert the device into the silo or to extract it therefrom,it is enough to operate the winches 16, 17 and 19 so as to bring the jib7 and the arm 11 into a substantially vertical position in order toallow them to pass through the manhole 2.

What is claimed is:
 1. A device for cleaning the wall (1, 23) of a silo,comprising a compressed-air gun (12) which can move inside the silo,characterized in that the gun (12) is suspended from two cables (14, 15)which are fixed respectively on either side of its centre of gravity andwhich are connected respectively to two separate winches (16, 17),bearing respectively on two pulleys (9, 10) fastened to a frame (6)which is arranged inside the silo and which is fixed to a rotary plate(4) which can move on a circular track (5) above an opening (2) in thesilo.
 2. The device according to claim 1, wherein one of theaforementioned pulleys (9) is mounted at one end of a jib (7) which ispivoted, at its other end (8), to the frame (6).
 3. The device accordingto claim 2, wherein the jib (7) is suspended from a cable (18) connectedto a winch (19).
 4. The device according to claim 2, wherein the winches(16, 17, 19) are located outside the silo, the cables (14, 15, 18)passing through a central opening (24) in the rotary plate (4).
 5. Thedevice according to claim 4, wherein the cables (14, 15, 18) bear onpulleys (10) fastened to the frame (6), beneath the central opening (24)in the rotary plate (4).
 6. The device according to claim 1, wherein thegun (12) comprises a stabilizing weight (13).
 7. The device according toclaim 1, wherein the winches (16, 17, 19) can be operated individually.8. The device according claim 1, wherein the gun (12) carries atelevision camera (20) connected to a receiver located outside the silo.9. The device according to claim 1, wherein the silo is intended tocontain powdered sodium carbonate.